But they crossed the same bridge from the wall of the stone chamber to the outside door in the starship’s side. All the starships dwelt inside an identical wound in the stone of the world, because all those wounds had been shaped by the forcefield that protected the starship and its passengers from all the effects of collision and sudden changes in inertia.

Rigg followed Vadesh carefully, trying to be aware of any new hazards, trying to notice all kinds of things he had overlooked before.

But the main thing Rigg searched for was the path of Ram Odin.

It was surprisingly easy to find, now that he knew it might exist. It was the oldest path in the starship. It was also the newest. It led again and again from the control room to the stasis chambers and then to the revival room and then back to the control room.

But in the past eleven thousand years, Ram Odin had not left the starship. Not since he crossed through the Wall from Ramfold.

Interesting. The Ram Odin that had been on the Vadeshfold copy of the starship had been killed by his expendable. And yet his path was here in the ship. A path markedly older than the already ancient passage of Ram Odin from Ramfold into Vadeshfold.

For a moment, Rigg wondered if that meant that the Ram Odin of this starship had not been killed; maybe all of them had lived, the way the Ram Odin of Odinfold had lived.

But no. That most ancient path moved throughout the ship, and then abruptly ended in the control room a few decades before another version of Ram Odin came through the Wall.

Thus Rigg learned the answer to a question that had bothered both him and Umbo ever since they learned about the starships. Paths were tied to the gravity of planets, and moved through space with the world where the paths were laid down. But when people were in space, their paths stayed with the ship transporting them. Unlike boat passengers on the Stashik River, whose paths stayed in the same position relative to the river, and not with the boats, the path of Ram Odin during the starship’s voyage stayed with the starship, even after the ship impacted with the planet’s surface.

I can see it all, thought Rigg. When the time comes, I can watch Vadeshex murder the Ram Odin of this starship.

But no. Being there as an observer would be hard to conceal from the expendable, who would then know there were such things as time-shifting humans from the future. It might cause the expendable—all the expendables—to behave differently. It might utterly change the course of history.

It couldn’t erase Rigg, of course—he and Umbo had settled that long ago. The agents of time change could not be undone by the shifts they themselves caused. They called it the “conservation of causality,” like the conservation of matter and energy. As causers, they had to remain in existence, even if the future they came from was otherwise erased.

But I’m not the only one whose existence I need to protect.

Rigg followed Vadesh to the revival chamber. “I need to do it here in case you have an adverse physical reaction,” Vadesh explained. “Loaf was robust and needed no life support. You might need to be sustained during your struggle for control.”

“When will you know if I’ve failed?”

“I’ll know,” said Vadesh.

“Tell me the symptoms that will lead you to that conclusion,” said Rigg.

Vadesh said nothing.

“I think I gave you a command.”

“I don’t have an answer,” said Vadesh. “I don’t know the symptoms that would lead to that conclusion, because you’re only the second person to receive one of this particular genotype of facemask, and the first one did not fail.”

“You’ve seen failure with early genotypes.”

“They were so different that they could not be the same.”

Rigg didn’t believe him. But should he show that, or would it lead Ram Odin—who was no doubt giving orders to Vadesh from his current location in the control room—to suspect that he knew too much?

“What concerns me,” said Rigg, “is that you might conclude that I had failed when I don’t think I’ve failed.”

“Here’s a simple test,” said Vadesh. “If you think, from my actions, that I have concluded that the facemask is in complete control, all you have to do to avoid my actions is to jump into the past and out of my reach.”

“Here’s a simpler test,” said Rigg. “I order you not to take any action at all concerning me and the facemask for three years, and even then you have to tell me what you’re planning to do.”

“In three years,” said Vadesh, “the Destroyers will be here.”

“That’s why I chose that number,” said Rigg.

Vadesh paused a moment, then said, “I will obey your command.”

“How nice of you. Did you have any choice?”

“I don’t have to obey a command that cannot take effect until after your death. But my programming does not permit me to regard facemask domination as death. Rather it is temporary disablement, so I will follow those rules instead of the death rules.”

“How nice of you,” said Rigg.

“You asked,” said Vadesh.

Rigg sat on the edge of the revival table. “Get me my facemask now,” said Rigg. “I assume you already have one picked out?”

“I have several dozen facemasks. I have no criteria for choosing one over another.”

“‘Several dozen,’” echoed Rigg. “You know an exact number. Say it.”

“One hundred and seventy,” said Vadesh.

“You have quite a supply of them. Expecting that many visitors?”

“It was to avoid that false conclusion that I used the term ‘several dozen,’” said Vadesh. “The large number is because that’s how many happened to survive and remain viable in stasis.”

“So you keep the facemasks in stasis,” said Rigg. “Like the voyagers in flight.”

“Someone’s been researching the starship,” said Vadesh.

“Yes, Umbo. And then he talked about what he learned.”

“Stasis and revival work almost identically for humans and facemasks, which is not a surprise, since these facemasks have been genetically designed for compatibility with humans.”

“Please get my facemask,” said Rigg. “Now.”

Vadesh left the room at once, and returned within the minute. “This one is as healthy as any other.”

“Then let’s . . .”

Rigg didn’t get to say “do it,” because the facemask flew out of the basin containing it. Did Vadesh fling it, or did the facemask somehow propel itself? Or had Rigg, without realizing it, bowed his head over the basin to look inside? He had only a split second to contemplate this question, and then there was agony and panic as his face was covered, his breath choked off, and tendrils inserted themselves with brutal irresistibility into his nostrils, his mouth, his ears and, most painful and frightening of all, his eyes.

This is irrevocable, he thought. My eyes are gone.

Then the tendrils reached through otic and optic nerves into his brain and the struggle began.

It was not like a tug of war. Not like a wrestling match. It was more like being lost in a maze. He could sense that his body was feeling things. Doing things. Yet he could not find his body, could not find the way to control his body.

It was as if the maze were constantly being changed so that nothing was in the same place twice, and barriers popped up where there had been no barriers before.

Pains came and went. His body needed to urinate. Then it did. It got up and walked, but not at Rigg’s command. It acted for its own reasons.

No, not its own reasons. The facemask’s reasons.

A rush of rejection swept over him; the feeling of hostility Rigg had seen in the faces of the people of Fall Ford when they gathered outside Nox’s house, intending to kill him in punishment for the death of Umbo’s little brother, whom Rigg had tried so hard to save. It was as if the facemask knew such a memory was there, and now used it to overwhelm Rigg with feelings and memories from his own past.